Existing wireless systems that utilize Long-Term Evolution (LTE) wireless communication standards (developed by the 3rd Generation Partnership Project (3GPP)) can be configured to deliver voice traffic between UEs (or other terminal-side devices) using Voice-over LTE (VoLTE). In systems using VoLTE, control plane signalling and media plane voice data is communicated between UEs over the Internet Protocol Multimedia Subsystem (IMS) using LTE data bearer, meaning that the voice call is conducted exclusively within the packet-switched domain.
To maintain high quality voice calls using VoLTE, operators often monitor the performance of voice calls over their networks using one or more KPIs. The KPIs for a particular voice call are often computed based on characteristics of voice call packets sampled by network- and UE-side data collection modules, or “probes,” which are situated along the voice call path. In addition, these probes can compute the KPI values from the observed characteristics and may analyze call data to determine overall call performance (i.e., end-of-call analysis at a whole-call level of granularity). Although insight into overall call performance can be helpful for determining whether a quality problem exists along the voice call path, existing systems have not used KPI data to provide insight into the sources of any quality degradation, nor have they utilized techniques for performing such analysis at higher levels of temporal granularity.